Figure 4

Predicted NINO 3.4 SST anomaly (red and blue curve) as compared with observed SST anomaly (black)⁴⁶ and the accuracy of prediction.

(A) The 10-daily values are for hindcast experiments during 1971–1973 derived from the case without seasonal control (Factor = 0: blue) and the optimized case using a seasonal adjustment factor (Factor = 1: red). Bars show errors estimated from standard deviation values of the ensemble forecasts. Grey shaded regions denote the boreal spring periods. (B) The same as (A) but for hindcast experiments during 2001–2003. Units are degrees Celsius. (C) Prediction error estimated by difference in root mean square differences for hindcasted NINO3.4 SSTs between conventional and advanced predictions for 7 El Nino events (red) and 3 events in a period of strong seasonality (green). Units are in kelvin.